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Plant diversity as the key to soil health

Gabe Brown isn’t afraid to put 25 species in the seed box

Bismarck, North Dakota — Gabe Brown acknowledges that no planted crop will build soil health as quickly and completely as a well-managed and very diverse perennial pasture. But that doesn’t mean he can’t try.

And boy, does he try. Gabe says the seed boxes on his no-till drill often contain 15 to 25 species at any one time, chosen from a wide variety of warm and cool season grasses and broadleaf crops. Buckwheat, barley, turnips, hairy vetch — you name it, Gabe plants it in mixes that give new meaning to the word “variety.” And he’s ready to use that seed at almost any time when winter isn’t ruling the northern Plains.

“We have the drill hooked up seven months a year. We’re seeding all the time,” Gabe says.

Photos: Paul Brown. Gabe Brown in a field full of diversity.

While cover crops are not all that unusual these days, Gabe and his son, Paul, are pushing the envelope to say the least, both in terms of what’s planted and how it is grazed. All of the crop ground here is seeded to cover crops during the course of the growing season. Whether it is crimson clover seeded with oats followed by a multi-species, post-harvest seeding for early winter grazing by the beef herd, or a wide array of warm seasons planted after winter triticale harvest to provide additional late-season grazing, the goal here is to keep the ground covered and a living root in the soil as much of the year as possible, often with highly diverse “cocktail” mixes of forages ranging from kale to triticale, and sudangrass to sweet clover — all with for the purpose of providing good forage yields while also building soils.

And the Browns’ beef herd — lately 350 cow-calf pairs and anywhere from 400 to 800 yearlings — takes the concept of mob grazing to new levels. A herd of 325 heifers has been stocked at a density of 685,000 lbs./acre, moving to new forage as many as seven times a day with the aid of solar-powered automatic gate openers. The Browns say they aim to have their cattle trample at least 60% of the available forage. All of the farm’s calves are forage grown and finished. The herds graze roughly 3,000 acres of “tame” and native dryland pasture in addition to providing natural fertilizer and a host of other soil health benefits to cropped ground.

None of the nearly 2,000 acres (both owned and rented) on which the Browns grow crops has been tilled over the past 20 years. “I will not till,” Gabe asserts. “Tillage destroys carbon, soil life, structure, infiltration and water holding capacity.”

These fields haven’t seen commercial fertilizers since 2008, and it’s been 12 years since any insecticides or fungicides were used. And after having applied herbicides once every two or three years in recent times, the plan for 2013 is to completely eliminate such applications and let the cover cocktails and mob grazing do their thing.

That thing is pretty darn impressive. Over the past two decades of no-till, Gabe has boosted the average organic matter levels of his crop ground from below 2% to above 5%, with most of that gain the result of multi-species covers combined with mob grazing of the beef herd. Soil health by any number of measures — tilth, water holding capacity, critter counts — has been considerably boosted and is visually superior compared to many neighboring fields.

While higher yield is not necessarily the primary objective, the results on this front are also impressive: At 127 bushels/acre, Gabe says his proven corn yield looks pretty good compared to the sub-100 bushel average for Burleigh County, which averages about 16 inches of annual precipitation. Gabe says his total cost for growing and marketing a bushel of corn last year came to $1.44 including a land charge. He says some of his best money is made by using the covers to extend grazing as late as February.

This much seed does cost something: the farm’s annual budget is roughly $25-$35/acre. And Gabe admits that after seven seasons of experimentation with cover cocktails, he and Paul have yet to come up with a foolproof “system” guaranteeing success.

Indeed, the Browns have developed a motto for their farming operation. “We want to fail at several things a year,” Gabe describes.

They’re not the only ones in this area who have become sold on cover crops. Jay Fuhrer, NRCS district conservationist for Burleigh County, says many of the area’s farms with both crops and cattle have shifted over to summer annuals for fall and winter grazing on portions of their land, thus taking important steps toward improving soil health and moisture retention in precipitation-challenged central North Dakota.

But no one in this county has matched the Browns in pushing the boundaries of what covers and grazing can do for the soil — and the bottom line.

“Gabe is just a flagship,” Jay describes. “His operation doesn’t fit a mold. He has no planned rotation on his cropland, and he uses that to his advantage. He’s trying to see how far he can go.”

Born of necessity

Like a lot of innovators, Gabe’s transition from conventional farming to cover cropping pioneer was born of necessity. Though he had already switched to no-till to conserve moisture, a combination of drought and hail caused four consecutive crop failures in the mid ‘90s and made it difficult to obtain the credit required to buy commercial fertilizer. So he began planting legumes for homegrown nitrogen along with other covers for cattle feed, and started noticing that the wheat planted to those acres often produced better than before.

But it was a few years before the concept of soil heath and the importance of diversity in promoting it really dawned on him. In the winter of 2006, Gabe and Jay attended a presentation by Dr. Ademir Calegari, a Brazilian agronomist who extolled the virtues of plant diversity in improving soil health and sustainable production. Jay went home and found some money to buy seed, planting plots ranging from one-crop monocultures to mixes containing as many as eight species.

It was a very dry year, and Jay had pretty much written off the trial when he stopped in to walk the plots. It wasn’t until he had returned to the car that it hit him: The monocultures were indeed dead, but the complex mixes were alive and growing. Indeed, the more species in the mix, the livelier the stand. Instead of competing, the more diverse array of species seemed to be helping one another to produce in a drought that was killing off the monocultures, with the benefits increasing in proportion to each plot’s diversity.

“This didn’t make sense in terms of classical thinking, but once you started thinking in terms of the diversity of nature, it made sense,” Jay explains. The native prairies of the northern Plains are some of the most diverse ecosystems on earth — Gabe says more than 140 species were counted in one of his native swards. This diversity, coupled with high-density bison grazing, built some of the world’s greatest soils. The native prairies are a prime example of complementary plants with a variety of strengths aiding each other, rather than competing as in the modern “crop vs. weeds” line of thinking.

The Burleigh County Soil Conservation District had already been moving away from building structures, and toward working with farmers to promote soil health as the best way to achieve its goals. In 2009 the district purchased 150 acres on which sustainable cropping and grazing systems would be employed to demonstrate improvements in soil health. The Menoken Farm is working with a wide variety of methods that break the conventional mold, including cocktail cover crops, mob grazing, compost applications and seeding in ways that encourage native pollinators and other beneficial insects.

“We are mimicking the native rangelands,” Jay describes. Yet he also notes that some of Gabe’s native pastures register above 7% organic matter. “His crop ground is at around 5%, so he’s got a long ways to go.”

Gabe says he is not enthusiastic about cash grain. “Perennial systems are by far the best as long as they’re highly diverse,” he acknowledges. “But (cash grain) is extremely lucrative right now, and I love toying with this cover cropping.” He likes proving that cropping systems can boost organic matter and overall soil health, which is something that the great majority of soil professionals thought impossible not too many years ago. Active on the speaking circuit, one of Gabe’s missions is to convince the cash-cropping world that cover crops, diversity, grazing and soil health are a far better route to the future compared to corn and bean monocultures and the associated production methods.

After hearing Dr. Calegari, Gabe started planting eight-species mixes, then 10, then 12, and soon enough it was a couple of dozen different seeds in the planter box. Last year the Browns even planted a 70-species mix on 20 acres that provided excellent grazing for cattle and laying hens, along with a variety of vegetables that were donated to the local food pantry. He says almost all species express themselves in even the most complex mixes, although growth of cool and warm seasons obviously varies based on the season’s weather.

“I am willing to try about anything once,” Gabe asserts. “I’ve proven it to myself. Diversity is always best. We can grow much, much more forage on much less rainfall.”

But is there any method to this madness? Yes, but perhaps no. Or at least not completely just yet.

The four main plant categories —broadleaf and grass, both warm and cool season — are planted by need and season. One example the Browns cite is harvesting a crop of winter triticale and hairy vetch and then planting a warm season cover that includes hybrid pearl millet, sorghum-sudangrass, soybeans, cowpeas, sunflowers, sunn hemp, clover, radishes and turnips. This cocktail can then be grazed anytime between October and February.

“To really make gains in soil health, you need full season cover crops — not just other cash crops,” Gabe asserts.

He also looks at the situation in any given field, addressing the resource concern on that particular field. For instance, too much litter on the soil surface means that there is too much carbon to allow proper nutrient cycling. More legumes and brassicas are added to the seeding mix to speed litter breakdown in the no-till system. “I like to see residue cycle through in a year’s time,” Gabe explains. “With diversity, you’re speeding up biological time. With 15 species you can gain 15 years of biological time in just one year.”

“This all depends on what you’re trying to accomplish,” he says. “You have to figure out your specific resource concerns. For instance, if a field is really low in organic matter, you’ll want to increase the number of species with a lot of root development.” He views cover crops as “primers” that start moving soils toward healthier status, with livestock integration providing an additional boost.

He admits to mistakes being made. Some species didn’t fit the environment. Others have proven incompatible, and cash grain yields have been hurt. Yet Gabe is reluctant to go into the details because “what didn’t work for me may well work in your situation. One of the problems with the current production model is that people are locked into their cookie-cutter recipes and are afraid to think outside the box.” Essentially, he’s saying that you’ll have to make your own mistakes.

Will it work elsewhere?

But can such tactics work in places with climates quite different from central North Dakota? “It can be done anywhere,” Gabe asserts, pointing to evidence from around the world that diversity and improvements in soil health can lead to greater agricultural productivity at lower costs. “I honestly believe you can make it work in any environment, although not within the current systems.” For instance, he says midwestern cash croppers will first need to expand their rotations by adding a crop such as winter wheat before starting to experiment with covers that can work in their situations. Dairy farmers who need to harvest high-quality winter feed will do things differently than cow-calf operators in the High Plains.

Jay agrees with Gabe’s views. “We don’t have recipes,” he notes. “But yeah, it will work in other parts of the country, perhaps even better than it does here. It does take a change in thinking though.”

In any event, if you want to pursue something akin to Gabe Brown’s cocktail cover program, keep your drill at the ready all season-long. Most of all, says Gabe, “You’ve got to wrap your mind around soil health.”